One of my friend got question 'Design Instagram/FB Live comment' in FB. Design a live commenting feature for FB/Instagram comments (new comments appear instantly). Can you please throw light how to go ahead with this question. I guess we need to use Publisher Subscriber using MessagingQueue? Each post will be topic. When some user U1 visit post P1, topic will be created if not already present for the P1 and U1 will be added both as producer and consumer for P1. Similarly for next users. Once somebody start typing in comment section and this action will be sent to all consumers and it will start showing "Somebody is typing" and once user post the comment, message will be sent to all consumers and post will start showing.